The present invention relates to a particle vibration damper which is associated with controlling vibration of a vibrating component and in particular a combustor system component of a gas turbine engine or a component of a machining operation.
The combustor system comprises a combustor chamber, a transition duct and an annular distribution chamber. The transition duct transmits hot gases from the combustion chamber to the annular distribution chamber, the hot gases then proceed into a turbine stage thereby driving the turbine.
In order to meet NOx (oxides of nitrogen) and CO (carbon monoxide) emission level requirements, turbulence of a fuel and air mixture is promoted to give acceptable combustion emissions. However, increasing the turbulence during the combustion process, to reduce emission levels, causes an increase of combustor noise which leads to an increase in vibratory stresses in the combustor system components. Combustor system components are vulnerable to high cyclic fatigue failure when the natural frequency of the component coincides or is close to coinciding with the acoustic frequency of the combustion process causing resonance of the component and consequently high vibratory amplitudes and hence high stresses in the component.
During a machining operation, for instance milling a metallic component, it is common for chatter to occur if the tooling or workpiece are of insufficient rigidity. Chatter is the vibration of the milling tool relative to the workpiece which results in either a reduction in the quality of the surface finish being machined or an increase in the machining process time where a better surface finish is required. In the manufacture, for instance, of aero-engine blisks this is of particular importance as the tough nature of the material, titanium, to be machined and the flexibility and low inherent damping of the workpiece severely curtails machining rates.
WO9812449 discloses a damping system for vibrating members of rotating hollow components of turbomachinery. The hollow components are filled with a low density (specific gravity of less than 1.5) granular fill which provides damping of frequencies in the range 100-500 Hz. SUMMARY OF THE INVENTION
It is an object of the present invention to provide a vibration damper for non-rotating engine components and in particular combustor system components of a gas turbine engine which increases the working life and reliability of the components.
It is a further object of the present invention to provide a particle vibration damper for damping vibrations of vibrating structures which may be temporarily or permanently disposed to regular or irregular workpiece and tooling geometries, may operate in extreme environmental conditions, may be used where access is limited and which has a reduced weight penalty.
According to the present invention there is provided a particle vibration damper for a vibrating component comprising a body having a chamber and a plurality of particles, the chamber partially filled with a plurality of particles, the particle vibration damper, in use, disposed to a vibrating component.
Preferably the particle vibration damper is mounted on a pedestal, the pedestal attached to the vibrating component.
Alternatively the body has more than one chamber.
Preferably each chamber is partially filled with particles of substantially the same size.
Alternatively each chamber is partially filled with particles of more than one discrete size. Alternatively each of the chambers is partially filled with a plurality of particles of substantially the same size, each plurality of particles in each chamber being of a different discrete size.
Preferably the particles are substantially spherical. Preferably the particles are substantially spherical with a diameter of 0.6 millimeters. Alternatively the particles are substantially spherical with a diameter in the range of 0.1 to 5.0 millimeters.
Preferably the particles are manufactured from steel but alternatively are metallic. Alternatively the particles are manufactured from ceramic material.
Preferably the chamber is filled with particles to between 95 and 100 percent by volume. More specifically, the chamber is filled with particles to 95 percent by volume. Alternatively each of the chambers is filled with particles to 95 percent by volume. Alternatively each of the chambers is filled with particles to a different percentage by volume of each chamber.
Alternatively, the chamber is filled with particles to a percentage volume fill such that the particles become fluidised by the vibrations of the vibrating component.
Preferably the body of the particle vibration damper is manufactured from steel, but alternatively any metallic substance may be used. Alternatively the body of the particle vibration damper is manufactured from ceramic material.
Preferably the body of the particle vibration damper is substantially cylindrical. Preferably, the cylindrical particle vibration damper comprises a D/r ratio of greater than 5. Alternatively the body of the particle vibration damper is substantially parallelepiped.
Preferably the body of the particle vibration damper comprises a chamber with a volume of 50000 cubic millimetres.
Preferably the vibrating component is an engine component. Preferably, the engine component is any one of the group comprising a transition duct, a combustion chamber. Alternatively, the vibrating component is any one of a workpiece, a machine tool, a machine. Preferably, the workpiece is subject to a machining operation.
Preferably the particle vibration damper is disposed to the vibrating component by temporary means.
Preferably the component, of the gas turbine engine, vibrates in the frequency range 200-1200 Hertz.
Preferably the gas turbine engine is an industrial gas turbine engine or alternatively a gas turbine engine for an aircraft or a gas turbine engine for a marine vessel.
Preferably a method of damping the vibrations of a vibrating component comprises the steps of, locating the position of the greatest amplitude of vibration on an engine component and disposing a vibration damping device on the component at the position of the greatest amplitude of vibration.